Synergistic effect of 3D-electrode architecture and FeS2 decorated graphene sheet as a catalytic cathode in lithium-sulfur battery

Lithium‑sulfur batteries (LSBs) show a five times higher energy density of 2600 W h kg−1 than the conventional Li-ion battery cathodes, thus satisfying the growing energy demand. The main challenge in LSBs is the polysulfide shuttle effect, causing severe capacity fade. Combining physical and chemical interactions to capture polysulfides can improve the long-term cycling performance and high sulfur utilization in LSBs. This work represents a rational design of FeS2-reduced graphene oxide (RGO) with high surface area carbon and sulfur composite (FRHS) onto a 3-dimensional (3D)‑carbon fiber (CF) electrode as an efficient electrocatalyst and the conductive network for LSBs. The FRHS@CF electrodes deliver an excellent initial discharge capacity of 1165 mAh g−1 at 100 mA g−1, and even at 500 mA g−1, it exhibits an initial discharge capacity of 740 mAh g−1 and maintains a stable capacity of 400 mAh g−1 with 73 % capacity retention at 325 cycles. The RGO and CF effectively shorten the path of Li-ion migration, improve electron transfer, and accommodate the volume effect of polysulfides with good electrolyte penetration. FeS2 effectively catalyzes the reaction kinetics of lithium polysulfides, thereby improving the reversibility with sulfur utilization.